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publications:1996macromolslippage [2011/12/17 20:05]
cgay
publications:1996macromolslippage [2016/01/19 11:06] (Version actuelle)
cgay
Ligne 7: Ligne 7:
 [[http://​pubs.acs.org/​doi/​abs/​10.1021/​ma950753j|Journal link]] -  [[http://​pubs.acs.org/​doi/​abs/​10.1021/​ma950753j|Journal link]] - 
 [[publications:​bibtex|BibTeX]] -  [[publications:​bibtex|BibTeX]] - 
-DOI:​10.1021/​ma950753j+[[http://​dx.doi.org/​10.1021/​ma950753j|DOI:​10.1021/​ma950753j]]
  
 **Abstract / Résumé** **Abstract / Résumé**
  
 We study the slippage of a highly viscous polymer melt (P monomers per chain) on a solid substrate grafted by a few smaller chains in the mushroom regime (N monomers per chain, grafting density nu). The friction is provided by the sliding motion of the P chains of the "​skin"​ (thickness Rp=P^{1/​2}a) which are entangled with the tethered chains. At low grafting densities, only a fraction of the P chains in the skin are coupled to the N chains, and the friction on the mushrooms is additive. Above a threshold nuc, all P chains of the skin are trapped, and the low-velocity friction becomes independent of the grafting density. Above a certain threshold slippage velocity V*(nu), the N chains are strongly stretched and reach the "​marginal state",​ corresponding to a constant shear stress. We expect that for nu > nuc, V*(nu) increases linearly. Depending on N, P, nu and V, we predict a cascade of regimes, where the N chains may be ideal, stretched, or "​marginal",​ while the trapped chains may be ideal or stretched and progressively disentangle from the N chains. We study the slippage of a highly viscous polymer melt (P monomers per chain) on a solid substrate grafted by a few smaller chains in the mushroom regime (N monomers per chain, grafting density nu). The friction is provided by the sliding motion of the P chains of the "​skin"​ (thickness Rp=P^{1/​2}a) which are entangled with the tethered chains. At low grafting densities, only a fraction of the P chains in the skin are coupled to the N chains, and the friction on the mushrooms is additive. Above a threshold nuc, all P chains of the skin are trapped, and the low-velocity friction becomes independent of the grafting density. Above a certain threshold slippage velocity V*(nu), the N chains are strongly stretched and reach the "​marginal state",​ corresponding to a constant shear stress. We expect that for nu > nuc, V*(nu) increases linearly. Depending on N, P, nu and V, we predict a cascade of regimes, where the N chains may be ideal, stretched, or "​marginal",​ while the trapped chains may be ideal or stretched and progressively disentangle from the N chains.
 
publications/1996macromolslippage.txt · Dernière modification: 2016/01/19 11:06 par cgay
 
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